Centrifugal casting



Mam-c119, 1937. M DU AS 2,073,199

CENTRIFUGAL CASTING Filed Dec. 19, 1933- 4 Sheets-Sheet 1 INVENTOR March9, 1937.

M. G. DUMAS CENTRIFUGAL CASTING 4 Sheets-Sheet 2 Filed Dec. 19, 1933INVENTOR March 9, 1937. M. G. DUMAS CENTRIFUGAL CASTING Filed Dec. 19,1953 4' Sheets-Sheet 3 INVENTOR Ma mw March 9, 1937. M DUMAS 2,073,199

CENTRIFUGAL CASTIN G Filed Dec. 19, 1933 4 Sheets-Sheet 4 Patented Mar.9, 1937 UNITED STATES CENTRIFUGAL CASTING Maxwell G. Dumas, Pittsburgh,Pa., assignor to The Dumas Engineering Company, Youngstown, Ohio, acorporation of Ohio Application December 19, 1933, Serial No. 703,086

4 Claims.

This invention relates to new and useful improvements in centrifugalcasting, more particularly to the centrifugal casting of ingots, bars,slabs and the like, and it is among the objects thereof to provide amethod of casting a plurality of ingots or bars by feeding the metalsimultaneously at both ends of the ingot bars or slabs.

Another object of the invention is the provision of apparatus wherebymolten metal may be fed to a double ended mold from a common source toseparate flow spouts while regulating the rate of flow in the separatespouts to prevent piping, such apparatus embodying themultiple pouringdevice of my Patents Nos. 1,915,650 and 1,915,651 granted June 27, 1933.

A further object of the invention is the provision of a mold structuredesigned to form a multiple of ingots or bars integrally in the form ofa squirrel-cage to maintain the cast bars in proper spaced relation toprevent their collapse in the mold after the speed of the mold has beenreduced, and to facilitate the removal of the casting from the mold;

Another object of the invention is the provision of a mold structure forcasting ingots or bars by centrifugal force which shall provide afourwalled form in which the bars are cast, and which shallsimultaneously provide means for controlling the thermal condition ofthe metal during the centrifugal casting operation.

Still a further object of the invention is the provision of means forcentrifugally casting shapes such as squares, rounds and otherstructural shapes.

These and other objects of the invention will become more apparent froma consideration of the accompanying drawings constituting a part hereofin which like reference characters designate like parts and in whichFigure 1 is a top plan view of a pouring device showing a mold forcentrifugal casting in sections; Figure 2 an end elevational view of thepouring device and crosssection of the mold taken at right angles to itsaxis of rotation; Figure 3, a cross-sectional view of a fragmentaryportion of the end of the mold taken parallel to the mold axis; Figure 4an en-' larged detail showingacross-sectionofthecastbar or ingot; Figure5 a top plan view of a pouring device and centrifugal casting mold, thelatter being in longitudinal section and embodying a refractory liner;Figure 6 an end elevational view thereof with the centrifugal castingmold in vertical section; Figure 7 a front elevational view partially insection of a modified form of centrifugal casting device with the moldaxes vertically disposed; Figure 8 a. transverse cross-sectional view ofthe mold; Figure 9 a cover member for the mold; Figure 10 a fragmentaryportion in side elevation of the top of the centrifugal mold; Figure 11a top plan view partially in section of a 5 modified form of mold;Figure 12 a cross-sectional view of a mold for centrifugally castinghexagonal bars; and Figure 13 a cross-sectional view of a mold forcentrifugally casting round bars.

My method of centrifugally casting ingots is 10 practiced by theemployment of a split mold I which consists of two or more sectionsjoined at the center line 2 and retained by a. cylindrical housing 3,Figures 1 and 3, to render it separable I for the removal of the castingtherefrom, the 15 mold housing 3 being supported on rollers 4, Figure 2,which are driven by a motor 5 through a suitable drive mechanism 6 tosubject the mold to rotary motion.

The particular mounting or drive mechanism of the mold is available inthe art and constitutes no part of the present invention.

The inner wall of the mold is provided with flutes or slots 1 inangularly spaced relation, the slots being the forms or matrices of themold in 25 which the ingots or bars are cast.

As shown in Figure 1 of the drawings, the slots 1 terminate into annularrecesses 8 at their respective ends, the recesses being provided withradial flanges or gates 9 which are adapted to retain the metal againstescape from the mold. The annular grooves 8 adjacent the ends of thematrices l are of shallow depth as compared with the matrix grooves land are chamfered or flared at 8a to feed the metal into the groovesfrom both ends so as to assure a sound homogeneous casting throughoutthe length of the ingot or bar.

The metal is fed to the annular chamber 8 by spouts Ill which projectinto the groove 8 and communicate at their upper ends with lips I I ofa. pouring receptacle l2, the receptacle being mounted upon journals l3,Figure 2, to render it tiltable, thereby controlling the flow of themetal.

The pouring receptacle l2 may be provided with a cover M which issuitably insulated by a refractory material to maintain the molten metaltherein at proper pouring temperature during the casting operation. Thereceptacle l2 may be adjustable horizontally to control the relativeflow of metal from the lip ll thereby obtaining suitable regulation toobtain equal volumes of flow to the respective spouts so that an equalamount of metal will be fed to the grooves of the mold from both endssimultaneously to eliminate discontinuity.

As shown in Figure 2, the pouring receptacle I2 is mounted on a suitableframe or support I! to provide the proper elevation for the gravity flowof the metal from the receptacle to the 5 spouts into the annular endcompartment 8 of the mold.

The operation of the above described, apparatus and the method ofpouring ingots, bars, slabs, etc., accomplished thereby is briefly asfoll lows:

With the two half-sections of the split mold mounted in the housing 3and with the housing supported on the drive rollers 4, the motor isenergized to actuate the mold causing it to rotate about its centralaxis, the speed of rotation being sufficient to produce the necessarypressure on the metal by centrifugal action to form a sound andhomogeneous casting. When the mold has been brought up to the properspeed of rotation, the pouring receptacle I! which has been charged withmolten metal is tilted about its journals l3 until metal begins to pourfrom the lip I I into the large portion of the spout ID from which it isconducted into the annular end 2 chambers 8.

As the end chambers are more shallow than the grooves l, the metal willbe subjected to the motion of the mold and then will flow downwardlyalong the chamfered faces 8a into the grooves 1. As the metal pouredinto the mold is subjected to the same speed as the speed of the moldwhen fiowing into the annular end chambers 8, it will readily flow intothe grooves 1 without striking the projecting portions of the moldbetween adjacent grooves thus assuring a smooth flow towards the centerof the grooves.

In conventional types of centrifugal casting apparatus, it has beendifficult to form sound ingots due to the fact that metal wascustomarily fed from oneend of the mold only, this difilculty beingovercome in the instant case by feeding the metal from both ends of thegrooves towards the center. spouts in may be regulated by tilting thereceptacle l2 more or less" to thereby control the density of the castingots or slabs and eliminate piping. When the mold grooves I- and theannular end grooves 8 have been filled to a proper depth with metal, thepouring receptacle I 2 is tilted to the position where the metal willcease to flow from the lip II and after the metal in the mold hassufilciently set, the motor! is deenergized and the cast structure isremoved from the mold by first removing the housing 3 and then splittingthe mold sections. Another method of controlling the amount of the metalfor each casting is to limit the capacity of the pouring receptacle sothat it must be completely emptied to supply the proper amount of metalto the molds.

The resultant structure is of squirrel-cage form having horizontal barsin annularly spaced relation with end rings integrally formed with thebars, these and rings being subsequently broken-off or cut from the barsand themselves formed into bars or ingots by splitting them andstraightening them in any suitable manner.

It will be seen from the foregoing description of this invention thatbythe provision of the end chambers cooperating with the axially disposedmatrix grooves, the metal will be given the proper direction of fiow andthe grooves will 75 grooves resulting in unsound ingots or bars,

The rate of flow from the Also. by utilizing the pouring receptacle withthe spouts on both ends of the mold, the metal fed to the mold can beregulated in any desired manner. One of the difllculties encountered inthe forming of ingots or bars by centrifugal casting is due to theporosity of the inner surface of the bars which is equivalent to thepiping formed in the casting of large ingots which necessitates theemployment of hot tops or sink heads for feeding metal to the center ofthe ingots as the metal sets. Similarly, it has been found that incentrifugal casting of bars, the matrix surfaces with which the metalcontacts produce a rapid chilling effect on the three sides of the barleaving the non-contacting inner surface with pipes or ruptures.

To overcome this difficulty, a refractory liner is employed as shown inFigures 5 and 6 of the drawings and which consists of the following:

A cylinder I 6 of refractory material such as clay is disposed centrallywithin the split mold sections 2, its end terminating in the annulargrooves at the end of the molds so that the longitudinal slots 1 areclosed on all four sides excepting at their ends where they communicatewith the annular grooves 8.

When the metal is fed from the spout ID of the multiple casting memberl2, it will flow in the annular grooves 8 and then from the groovesthrough the respective ends of grooves towards the center of the mold,the metal being in contact with the three sides of the groove 1 and theouter wall surface of the cylinder l6. 'I'hemetal fills the grooves anddisplaces the air, while in molds where the liner I6 is not employed themetal will oxidize rapidly due to its contact with excess hot air underpressure caused by the rapid rotation of the mold. The cylinder l6 maybe preheated if desired in any suitable manner although this can bedispensed with if desired as the refractory substance of the cylinder I8will prevent excessive chilling of the inner surface of the cast bars sothat the metal will feed towards the .center of the bars or ingots inthe same manner as the metal blowing from a sink head or hot top in thestationary pouring method.

When the bars have been cast in the manner heretofore described, theouter shell 3 of the mold is removed and the split mold section droppedoff leaving the cast bars integrally joined with the annular rings 8 andwhen these rings are knocked oil at their thin sections at the chamferedportion 8 of the bars, the bars will be removed from the refractorycylinder IS without even recessitating the breakage of the cylinder.

In Figures '7 to 10 inclusive of the drawings, I have shown amodification of the centrifugal casting device of Figures 1 to 6inclusive in which the mold generally designated\by the numeral "is aconical shell l8 provided with bosses I 8 by means of which it issecuredto a tum table 20 by the wedges 2|. I

The upper portion of the shell I8 is provided with a track 22 forengaging rollers 28 of a pair of hinge arms. 24 that are pivoted to thebase 25' thereof in the manner shown in Figure 8 to isolate the slots28.

A clamping ring is placed on the top of the mold and shell l1 and I8,and is secured to lugs 3! by wedges 32.

The turn table 20 is actuated through a bevel gear drive 33 and a primemover designated at 34.

A pouring receptacle I! with spouts I0 is provided and is preferablymounted on trunnions to be tiltable, and'the trunnion members in turnmay be mounted on a. track so that the pouring receptacle may beemployed to serve a plurality of centrifugal molds arranged in groupswith two of such molds in alinement so that two sets of castings can bepoured simultaneously.

The metal is cast through spouts l0 into an annular space 36 provided atthe top of the mold from which the metal feeds downwardly into thetroughs 28 between the refractory center 29 until the slots or grooves28 are filled to the top and the formation of piping in the bars isprevented by'the refractory center 29 in the same manner as explained inconnection with the liner of Figures 5 and 6 of the drawings.

When the castings are completed, the arms 24 are swung back and theshell or housing It is removed permitting the liner and bars to bestripped from the mold.

In the structure shown in Figure 11 the mold is bellied to acceleratethe flow of the metal from the annular chambers at the respective endsto the center. The construction is identical with that of Figure 5excepting that both the matrix or grooves 'l of the mold and the liner Iare of bellied shape.

In Figure 12 the mold I and liner l6 each constitute matrix portions and40a for casting hexagonal bars and, Figure 13, round bars. When theliner i6 is grooved to constitute such matrix portions it is necessarilyof heavier wall sections than if the liner is employed as a straightside as in Figures 5 and 6.

Although one embodiment of the invention has tee herein illustrated anddescribed, it will be obvious to those skilled in the art that variousmodifications may be made in the details of construction withoutdeparting from the principles herein set forth.

.inner wall of said mold, a liner complementary in shape to the innerwall of the mold and in contact with said wall, and means at therespective 'ends of the mold for simultaneously feeding molten metalinto said axially disposed grooves from both ends of said grooves.

3. Apparatus for centrifugally casting metal comprising a rotatable moldhaving a hollow interior and a liner in engagement with the inner wallof said mold, said mold and liner having flutes or grooves formed intheir contacting surfaces, the flutes or grooves being in 'alinement -toconstitute matrices of bars of predetermined shape, means for actuatingthe mold to subject it to rotary movement, and means for feeding metalinto the ends of the grooves while said mold is rotating.

4. Apparatus for centrifugally casting metal comprising a metal mold ofsubstantially cylindrical form mounted for rotary movement, means foractuating said mold, said mold being of hollow construction and havingmatrices on the inner surface thereof extending to the ends of saidmold, a liner disposed within said mold with its outer surfacecontacting the inner surface of the mold, said liner having matrices incooperative alinement with the matrices of said mold, the matrices ofthe mold and liner cooperating to form castings of predetermined shape,and means for feeding molten metal into the ends of said matrices whilethe mold is subjected to rotation.

MAXWELL G. DUMAS.

